The present invention is directed to highly dispersive dry powder compositions, and in particular, to highly dispersive, inhalable dry powder compositions for aerosolized delivery to the lungs. The dry powders of the invention contain an active agent and a di- or tripeptide containing at least 2 leucyl residues, and are physically and chemically stable upon storage. The powders of the invention also demonstrate superior aerosol performance.
Traditionally, inhalation therapy has played a relatively minor role in the administration of biotherapeutics and conventional pharmaceuticals when compared to more traditional drug administration routes, such as oral and intraveneous. Injection is the customary route of delivery of biotherapeutics (e.g., peptides, proteins and nucleic acids), and due to the many drawbacks associated with injection (e.g., inconvenience, discomfort, patient aversion to needle-based delivery methods), alternative administration routes are needed.
Pulmonary delivery is one such alternative administration route which can offer several advantages over subcutaneous administration. These advantages include the convenience of patient self-administration, the potential for reduced drug side-effects, ease of delivery by inhalation, the elimination of needles, and the like. Many preclinical and clinical studies with inhaled proteins, peptides, DNA and small molecules have demonstrated that efficacy can be achieved both within the lungs and systemically. However, despite such results, the role of inhalation therapy in the health care field has not grown as expected over recent years, in part due to a set of problems unique to the development of inhalable drug formulations. Dry powder formulations, while offering unique advantages over cumbersome liquid dosage forms and propellant-driven formulations, are prone to aggregation and low flowability phenomena which considerably diminish the efficiency of dry powder-based inhalation therapies.
Particulate aggregation, caused by particle-particle interactions, such as hydrophobic, electrostatic, and capillary interactions, must be minimized in order to provide dispersible powders for effective inhalation therapies. Various approaches have been utilized in efforts to prepare dry powders having minimal particle aggregation and good aerosol properties. These approaches include the modification of dry powder particle surface texture (Ganderton, et al., U.S. Pat. No. 5,376,386), the co-delivery of large carrier particles (absent drug) with therapeutic aerosols to achieve efficient aerosolization, particle coatings (Hanes, U.S. Pat. No. 5,855,913; Ruel, et al., U.S. Pat. No. 5,663,198) aerodynamically light particles (Edwards, et al., U.S. Pat. No. 5,985,309), use of antistatic agents, (Simpkin, et al., U.S. Pat. No. 5,908,639) and the addition of certain excipients, e.g., surfactants (Hanes U.S. Pat. No. 5,855,913; Edwards, U.S. Pat. No. 5,985,309). Unfortunately, the formation of particulate aggregates and production of powders having poor flow properties and low dispersivities continue to plague development efforts to prepare aerosolizable dry powders for inhalation therapy. Thus, a need exists for improved inhalable aerosols for the pulmonary delivery of therapeutic agents, and in particular, for dry powders having excellent aerosol properties and reduced particle-particle interactions, irrespective of the therapeutic agent.
The present invention is based upon the discovery of a particular class of excipients, which, when incorporated into dry powder formulations for aerosolization and delivery to the lung, notably improves the dispersivity and aerosolization properties of the dry powders, irrespective of the type of active agent contained in the formulation. More particularly, the invention provides a dry powder composition which comprises an active agent and a di or tri-peptide comprising at least two leucines. Preferred di- and tripeptides are those which are surface active.
The dry powder of the invention typically contains from about 2% by weight to about 99% by weight di- or tri-peptide, and may optionally contain additional excipients or carriers, such as carbohydrates, amino acids, peptides, proteins, organic acid salts, and/or polymers.
The presence of the di- or tri-peptide is effective to notably increase the emitted dose of the dry powder over the emitted dose of the powder composition absent the di- or tri-peptide. In one particular embodiment of the invention, the dry powder of the invention is characterized by an emitted dose of at least about 30%. In another embodiment, the concentration of the dileucyl- di- or tri-peptide on the surface of the particles is greater than in the bulk powder.
Additional features of the dry powder particles of the invention include, in one embodiment, a mass median diameter of less than about 10 microns, and in yet another embodiment, a mass median aerodynamic diameter of less than about 10 microns. In yet another embodiment, the dry powder comprises particles having a bulk density from 0.1 to 10 grams per cubic centimeter.
The dry powder of the invention is further characterized by both physical and chemical stability upon storage, as characterized, in one embodiment, by a drop in emitted dose of no more than about 10% when stored under ambient conditions for a period of three months. In another embodiment, the chemical stability of the dry powder is characterized by degradation of less than about 5% by weight of the active agent upon storage of the dry powdered composition under ambient conditions for a period of three months.
In another aspect, the invention provides a method for enhancing the aerosol performance of a dry powder. In the method, a di- or tri-peptide is incorporated into an active-agent containing liquid formulation. The resulting liquid formulation is dried to produce a dry powder containing the active agent and the di- and/or tripeptide, whereby the resultant dry powder possesses an emitted dose that is increased over the emitted dose of a dry powder having the same components but absent the di- or tripeptide.
In one embodiment of the method, the liquid formulation is an aqueous formulation. In another particular embodiment of the method, the liquid formulation is spray-dried to produce a dry powder.
In yet a further aspect, the invention provides a method for increasing the aerosol performance of an active-agent containing formulation suitable for administration to the lung. According to the method, a di- or tripeptide comprising at least two leucines is incorporated into a formulation comprising an active agent. The resulting composition comprising the active agent and the di- or tripeptide possesses an emitted dose that is increased over the emitted dose of a composition having the same components but absent the di- or tripeptide. In one embodiment, the method results in a liquid composition suitable for aerosolized administration to the lung; in an alternative embodiment, the method results in a dry powdered composition suitable for aerosolized administration to the lung.
Yet another aspect of the invention is directed to a method for delivery of a dry powder composition to the lungs of a mammalian subject by administering by inhalation the compositions of the invention as previously described, in aerosolized form.
These and other objects and features of the invention will become more fully apparent when the following detailed description is read in conjunction with the accompanying figures and examples.